1. Field of Invention
The present invention relates to a test method of an embedded capacitor, and more particularly, to a test method of an embedded capacitor and test system thereof, for determining an electrical specification of the embedded capacitive component in a circuit board substrate, thereby avoiding execution of follow-up fabricating processes for circuit board substrate which does not satisfy desired specifications.
2. Related Art
Along with the development trend of electronic products towards high functionality and small size, the lamination technology of the circuit board substrate must be provided with characteristics such as thin thickness, multiple layers, and high density. Therefore, in order to create a bigger space in a limited circuit board substrate area, and enhance the module versatility, a circuit board substrate in which passive components such as resistors, capacitors, and inductors are embedded is developed, thereby creating more space to construct active components, and enhancing the performance of the integral device.
However, the electrical property of the dielectric layer may be unstable because of a variation of the organic material during the process or the material unevenness. In particular, the properties of the embedded components and the high-frequency material must be mastered accurately during the fabrication. Therefore, in an early stage of material development, properties such as the dielectric value of material, the lamination thickness of circuit board substrate, the metal roughness, and even the moso phase change must be measured carefully, to avoid executing a follow-up fabricating process for the circuit board substrate with embedded components not satisfying the desired specification, thereby reducing the electronic product yield, causing a resource waste, and increasing the cost.
As shown in FIG. 1, it shows a conventional circuit board substrate with embedded capacitive components. A conductive metal sheet 12, a dielectric thin plate 14, and a conductive metal sheet 16 are stacked sequentially to form a capacitive circuit board substrate 10, as shown in the U.S. Pat. No. 5,155,655. In a conventional measuring method, the electrical property of each capacitive component can only be obtained through careful measurement one by one. Also, for this circuit board substrate, the capacitive components are embedded, and therefore when measuring, the measured joints of the capacitive components must be connected with the test pad disposed on the surface of the circuit board substrate by a lead, for carrying out the measurement through the test pad. However, this manner is rather complicated and time consuming for a large number of measurements.
It can be known that, at present, there is no efficient measuring method for measuring the embedded components. Conventionally, a test pad must be formed when carrying out electrical measurements and the electrical properties will definitely be damaged. Therefore, when designing an ordinary circuit, the fabrication will need to be performed twice, to slightly adjust the variation in each process.
Therefore, it is a project to be researched by those related in the art that providing a method for determining whether or not the embedded capacitive components, such as capacitors, baluns, and filters, in the entire circuit board substrate satisfy set electrical specifications (not carrying out an open/short test only).